New Mexico Geological Society Annual Spring Meeting — Abstracts

Associated dinosaur skin impressions and bones were collected at NMMNH locality 1417 in the Upper Cretaceous (Campanian) Ringbone Formation of southwestern New Mexico. This locality is in the middle member of the Ringbone Formation in a 0.7-m-thick sandstone bed that is 58 m above the highest of two laterally persistent volcanic tuffs. This portion of the Ringbone Formation records lacustrine deposition. Lacustrine facies associations begin with trough-crossbedded sandstones and conglomerates (very shallow water deltaic) followed by ripple-laminated sandstones and siltstones (shallow water lacustrine) culminated by black, sulfurous, thinly laminated shale (deep water lacustrine). The sandstone bed that contained the skin impressions and bones represents a shallow water, distal deltaic facies . Impressions of palm leaves (Sabalites sp.) in these strata indicate a frost-free, subtropical to tropical climate.

The skin impressions are preserved as patctles of tubercles predominantly along a Single bedding plane in both positive and negative relief; with the former representing a cast of the original impression surface. The patches occur in association with part of the caudal skeletal section that includes 16 articulated vertebral centra from the distal tail region and ossified tendons.

Detailed examination of the impressions reveals that the integument morphology is characterized by polygonal tubercles with mean dimensions of 7.4 x 5.4 mm. The largest tubercle measured is 17.0 x 14.5 mm. Radiating grooves extend from the top to the base of each tubercle. There is significant variation in tubercle density between patches, which ranges from 36 to 475 per 25 square cm. Overall, the integument is comparable to previous descriptions of hadrosaur skin impressions. A hadrosaurian affinity for this individual is also supported by the presence of numerous ossified tendons, which are known from the tail section of these dinosaurs.